An IGBT structurally includes an emitter region of a first conductivity type (an n-type, for example) and a drift region of the first conductivity type separated from the emitter region by a body region of a second conductivity type (a p-type, for example). As described in Patent Literature 1, a technique of inserting a barrier layer of the first conductivity type into a body region of a second conductivity type so as to divide, by the barrier layer, the body region into a part in contact with an emitter region and a part in contact with a drift region is known. According to this technique, minority carriers are suppressed from permeating into an emitter electrode from the drift region, and conductivity modulation can be enhanced to decrease resistance of the IGBT in an on-state (to decrease an on-state voltage).
Patent Literature 1 discloses another technique of incorporating an IGBT and a Free Wheeling Diode in a single semiconductor substrate to realize a Reverse-Conducting IGBT (an RC-IGBT). Yet another technique is known, in which an IGBT and a diode are incorporated in a single semiconductor substrate to prevent, for example, breakage of a gate insulating film.